Power-generating system.



' C. S. BRADLEY. POWERGENERATING SYSTEM.

APPLICATION FILED OCT. 12. 1916.

1,250,087. I Patented Dec. 11,1917.

2 SHEETS-SHEET Inventor Charles SBFadIe b5 Wm;

H is Attorneg.

C. S. BRADLEY.

POWER GENERAHNG SYSTEM. APPLICATION FILED OCT. 12,1916.

Pzitented 11%.- 11,1917.

2 SHEETS-SHEET 2.

Charles SBradleH,

His Attorneg.

CHARLES S. BRADLEY, OF NEW YORK, N. Y., ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

POWER-GENERATING SYSTEM.

Specification of Letters Patent.

Patented Dec.'11, 191'?o To all whom it may concern:

Be it known that I, CHARLES S. BRADLEY, a citizen of the United States, residing at New York, county of New York, State of New York, have invented certain new and useful Improvements in Power-Generating Systems, of which the following is a speci- 'fication.

The present invention relates to power generating systems-in which an elastic fluid is employed as the motive power agent, and has for its object to improve their efficiency by increasing the temperaturerange over which they operate without, however, correspondingly increasing the pressure of the elastic fluid.

In carrying out my invention in its simplest form I employ what may be termed an initial boiler of any suitable construction containin a salt, such as caustic potash, or its equiva ent, and water forming a rather highly concentrated solution, said boiler being heated by a. combustible in any usual way to the desired high temperature. Due to the use of such a solution it follows that the pressure for a given temperature will be materially less than would be the case with water under similar conditions. Steam generated in the boiler is delivered in a more or less superheated condition to a prime mover, such as a turbine, or other con- .sumption device in which useful work is performed, and the exhaust therefrom as it is condensed is caused to give up heat to another fluid having a lower boiling point, such as water for example. The steam thus generated is supplied to the same prime'mover Y or consumption device which utilizes the steam flux from the initial boiler, and after performing useful work is condensed in the sels in heat conducting or transmitting relation to each other whereby heat can readily pass from the content of the vessel of higher temperature to that of the lower. In the condenser portion is maintained a solution of caustic potash and water, but of a concentration less ordinary manner, as by a surface or jet condenser wherein a certain amount of heat is prime mover.

than exists in the initial boiler, and hence of .a lower boiling point. This condenses the steam at approximately the boiling point temperature of the solution. .In the boiler portion of the condenserboiler is maintained a body of fluid having a lower boiling point, and which delivers vapor under some certain predetermined pressure to said'prime mover.

The delivery of steam from the initial boiler and the condensation of steam in the condenser portion of the condenser-boiler would rapidly increase the concentration in the boiler and weaken it in the condenser. To maintain the proper concentration in the initial boiler water is supplied thereto by suitable means and in amounts equivalent to the steam discharged. Means are also provided for continuously causing an exchange of solutions between the initial boiler and the same kind of vapor. The advantage of this over other systems heretofore proposed for utilizingtwo fluids of different boiling points resides in the fact that the vapors.be ing of the same kind can be used simultaneously in the same prime mover or other consumption, device without having to provide means for keeping the fluids and their vapors separate from one another at all times. This also permits of connecting the condensers in'multiple relation sothat the final pressures will be the same in all cases and the work of condensing will be divided between,

the condensers in proportion to their capacities to condense steam. In other words, the generation of the same kind of vapor in the different parts of the system results in amaterial simplification of the apparatus as a whole. Furthermore, by properly organizing and arranging the parts of the system steam fluxes from the initial boiler and condenser-boiler may be obtained having the same or different pressures as desired. By arranging the boilers to deliver steam at the same, or substantially the same, pressure, they may both discharge into the same main or header, or the steam therefrom maybe delivered'directly to the inlet of the same If the ressures differ the steam fluxes can still be delivered to the same prime mover by admitting the one 01 higher pressure to the main inlet and the one of lower pressure to an inlet in a succeeding stage.

As an illustration, in a two-unit system as above described, I may employ a caustic potash solution of about 85% in the initial oiler and derive steam therefrom at about 225 pounds pressure. In the condenser receiving the exhaust the solution will be of the same character, but somewhat weaker, say 83.5% for example. From the boiler associated inv heat conductive relation therewith steam at about 225 pounds may be obtained using water as a fluid, and the steam from both boilers may be delivered to the same prime mover if desired. In addition to the solution containing condenser, a final condenser, as stated above, is employed in which circulating water is employed as in ordinary cases.

Instead "of a two-unit system, I may provide a greater number of units, in which case the initial boiler will have a fluid of relatively high concentration and high boiling pointfand the succeeding condenser-boilers will have successively lower concentrations of the's'ame fluid, and hence lower boiling point, each concentration being determined by the amount of heat available in the exhaust from the preceding boiler. All the condenser-boilers will contain a fluid having a boiling point greater than that of water, except the last boiler in Which water alone will be employed.

Taking as an example, a five-unit system; in the first boiler I use a solution com ris ing 100 parts of water by weight and a out 623 parts of caustic potash also by weight, the boiling point of which is about 644 F. at atmospheric pressure. A striking difl'erence between the present system and one using water alone as the fluid is found in the fact that Water heated to 644 F. in a boiler will give ofl steam of about 1200 pounds pressure per square inch as contrasted with steam at atmospheric from said solution. For the solution in the second boiler I use 100 parts of water and about 375 parts of caustic potash boiling at about 536 F. For the third boiler I use 100 parts of water and about 219 parts of caustic potash boiling at about 428 F. For the fourth boiler I use 100 parts of water and about 121 parts of caustic potash boiling at about 320 F. In the last boiler water alone is employed boiling at 212 F. The steam from this last boiler, after performing useful work is condensed in a fi'nal condenser of ordinary construction. The above reference to graduated temperatures is by way of illustration and not as a limitation of my invention.

It is evident that in the broader aspect of my invention the number of units can be made small or large, but generally speaking, it will be preferable to use a smaller rather than a larger number on account ot the losses which must inevitably occur in the various transformations. It is also to be noted that the relationship of solutions and temperatures will change with the pressure in a system of the character described and that said pressures will vary with different conditions of service.

In the accompanying drawings which illustrate my improved system diagrammatically, Figure 1 is a diagrammatic view in outline of the various parts showing their relation one to the other; Fig. 2 is a detail view in section of a part of the system, and Fig. 3 is a detail view of a pump for pumping the solution between the boilers and condensers.

I will first briefly describe the system as embodied in Fi 1 and later describe in detail theconstruction of the several parts. 5 indicates an initial boiler of suitable construction which contains a high concentration of caustic potash and is heated in any usual way, as by the use of oil burners or a coal fire 6, the waste products of combustion escaping by the stack. The steam generated passes through the main 7 to the prime mover 8 or other steam consuming device. As shown, it is a turbine of the Well known Curtis type exhausting into the main 9. The exhaust steam (considering only for the moment the first element of the system) is discharged from the main into the condenser portion 10 of a condenser-boiler, said condenser portion containing asolution of caustic potash of less concentration than that in the initial boiler. Condensate from thecondenser is returned to the initial boiler 5, to maintain the desired degree of concentration therein, by means of a rotary feed pump 11, said condensate on its way to the boiler passing through a heat exchanger or economizer l2 and receiving heat therefrom. The amount of fluid delivered by the pump may be controlled in any desired manner, as for example, by varying its speed, or stroke. A limited amount of hot and highly concentrated solution taken from the initial boiler passes by pipe 13 through the exchanger 12, and in so doing gives up a share of its heat to the fluid of lesser concentration delivered by the pump 11 and then passes through a regulating and feed pump '14: to the upper portion of the condenser 10 into which it is sprayed in any suitable manner. The particles of the cooled solution in falling assist the solution in the condenser in condensing the exhaust from the turbine. The construction of the heat in the condensation on the one hand, and

in the vaporization of fluid in the boiler on the other, a continuous circulation of fluid is maintained through a condenser by means of a pump 16, the latter receiving its supply from the well 1.7 by pipe 18 and delivering it to the pipe 19 in common with the pump 14. The details of this are best shown in Fig. 2. The steam generated in the boiler 15, and which, by reason of the degree of concentration of the solution has the same pressure as that in the initial boiler 5, flows by the pipe 20 to the main 7 and thence to the turbine. It will thus be observed that boilers 5 and 1.5 supply steam in multiple to the same main for use in one or more devices connected thereto.

21 and 22 indicate respectively the condenser and boile portions of an additional unit of the system, said unit being constructed, arranged and connected in the same manner as that previously described, the only difference being that the degree of concentration of the caustic potash is less than in the preceding parts. The condenser-boiler has associated with it the heat exchanger 23 and the pumps 24, 25 and 26, all of the character above described in connection with the first unit.

27 and 28 indicate respectively the condenser and boiler portions of an additional unit of the system, said unit being constructed, arranged and connected in the same manner as those previously described, the only difference being that the degree of concentration of the caustic potash is less. The condenser-boiler has associated with it the heat exchanger 29 and the pumps 30, 31 and 32, all operating in the manner previously described.

In the last condenser-boiler the conditions are different, and this, whether one or more solution containing units are interposed between it" and the initial boiler. Exhaust from the main 9 enters the condenser portion 33 of the boiler and is there condensed, the condensate beingreturned to boiler 28 through a heat exchanger 33*. In this part' of the system the solution is the least concentrated of all. In the boiler portion 34:, however, instead of using caustic potash in solution, water alone is employed and supplied by the pump 35 from the final condenser 36, the latter being shown as of the surface type and provided with an inlet pipe 37 and an outlet pipe 88 for the passage of circulating water. Associated with the last mentioned condenser-boiler are pumps 39, 40 and 41 operating in the manner previously described. Any make up water made necessary by reason of leakages can be supplied in the ordinary manner.

Referring to Fig. 2, the boiler 5, in the example illustrated, is provided with tubes 45 through which the hot gases from the pumped. The pumps are fire on the grate 46 pass and in so doing give up their heat to the solution contained in the surrounding structure. The waste gases escape through the stack 47. The boiler is provided wlth any suitable support, such as a brick work, that also assists in defining the fire chamber and flues. 48 indicates 'a steam dome from which steam is withdrawn for the system, and 49 a safety valve associated therewith and set for any predetermined pressure. 50 indicates a manhole and cover whereby the boiler may be charged with potash andthe interior inspected when desired. p

The heat exchanger 12 is, or may be constructed in a manner similar to the ordinary surface condenser. It comprises, in the present example, a tubular shell 51 and heads 52. Between the shell and heads are tube sheets 53 to which the ends of the tubes are secured. The space surrounding the tubes contains the hot highly concentrated solution from the boiler, and the tubes themselves and chambers in the heads contain the weaker and colder solution returned from the condenser portion 10 of the condenserboiler.

The pumps here given as an illustration are of the Connelville type, Figs. 2 and 3. For simplicity a common casing is provided for the three, there being suitable partitions between the impellers. Each pump has a pair of rotating members 54 mounted on separate shafts, One ofwhich is driven by a pulley 55 from a suitable source of power. Each pump casing is provided with an inlet and an outlet for the passage of fluid being driven by an elec tric motor 55*, the speed of whichcan be varied by moving the rheostat arm 55 to vary the strength of the field magnet. By varying the speed at which the pumps are driven, or varying the effective delivery in any well known manner, the amount of solution passing between the boiler and the con denser-boiler associated therewith can be.

regulated. The reason for employing these pumps will be evident when it is remembered that the solution should be kept as nearly as possible at the concentration determined upon for the operation of the different boilers. If insufficient water is supplied to the boilers the concentration Wlll become greater,

of the fluid will be raised. On the other hand, if the-solution becomes too weak its boiling point will be unduly lowered.

Referring now to the condenser-boiler,

Fig. 2, 10 indicates the condenser portion containing a caustic potash solution weaker than that in the preceding boiler, and. which is made in the form of a tower 56 having perforated trays 57 or equivalent .devices extending transversely thereof. The highly concentrated fluid from the heat exchanger,

and hence the boiling point 12 is discharged from the pipe 19 by a rose spray or head 58 and mingles with and assists in condensing the exhaust steam admitted from the exhaust steam pipe 9. In the lower part of the tower isa well 59 from which fluid is returnedto the initial boiler ,5 by the pump 11, the fluid passing through the heat exchanger 12 and receiving heat therefrom prior to entering the boiler. 60 indicates the casing of the boiler portion of the condenser-boiler. In the lower part thereof are tubes 61 supported by tube sheets 62. The condensate from the condenser passes through the tubes and gives up its heat to the solution contained in the boiler portion. The steam generated in this manner is discharged to the main steam pipe or header 7 by the pipe 20. Condensate enters the well 17 from which it passes by pipe 18 to the pump 16 which, with the pipe 19 and spray head 58 maintains an active circulation ofthe fluid in the condenser.

As is well known, the passage of heat through a heat conducting material is proportional to the difi'erence of tem erature per unit area, hence the amount 0 evaporation in each condenser-boiler is the difierence of temperature times the area of the conductin surface. I establish the desired relationship between the initial boiler, the condenser-boiler, and the final condenser by graduating the surface of each successive devlce, constructing them so that each has a certain smaller amount of surface proceeding toward the final condenser. To provide for an accurate adjustment or regulation of the surface relations, a means is provided in each condenser-boiler whereby its active surface may be increased or decreased at will until the difference of temperature is divided between them in the proper ratio. As an illustration of a suitable means for the pur pose, one or more valves 65 are provided by means of which one or more condenserboil'er tubes can be cut into and out of service, thereby changin the surface area to an extent represented y said tube or tubes. In the top of the boiler is a manhole and cover 66.by means of which caustic potash can be supplied to the boiler when the system is. shut down and through which the interior of the boiler can be inspected. Similar means 67 are also provided for introducing a solution of proper character to the condenser' portion.. The condenser-boilers and pumps of the other units of the system are constructed in a similar manner and hence further description of them seems unnecessary.

I prefer to use combined jet and surface condensers because by so doing the steam can be brought into finely sub-divided contact with the solution and in this manner a rapid condensation is obtained.

The feature of discharging steam from all memos? the boilers in multiple into a common main from which it flows to the prime mover or tween a condenser and the boiler from which its steam is received must also be the same in order to maintain the proper concentration of the solution in the respective parts of the system.

For many purposes it is desirable to operate the system with small temperature differences between the parts of each condenserboiler and this can be done without making the parts unduly large, as will be seen from the following: Assume a 5 F. temperature difierence and 700 B. T. Us. transmitted per degree for each square foot of surface per hour, or a total of 3500 B. T. Us. per square foot per hour; also that 2640 B. T. Us. are required per hour to develop one horse power and that the efliciency of a single condenser-boiler is 8%. We will then have to be transmitted per horse power hour, and 33000 divided by 3500=9.4 or roughly ten square feet of surface, which is well within economical limits.

Reference has been made to the importance of maintaining the proper solutions in the difi'erent parts of the system and of varying the active surfaces of the condenser boilers to meet varying conditions and suit able means for attaining this result have been described. The stability of equilibrium thus obtained isfurther aided by the fact that there is a quantity of stored energy in the solutions which is always available. Assuming that the system is operating nor- ==33,000 B. T. Us.

mally and a sudden increase of load on the prime mover takes"place accompanied by a decrease of pressure of the supply of steam.

This reduction of pressure will cause a greater difference of temperature between the sides of the heating surfaces and an increased flow of heat will result accompanied by an increased quantity of steam, with the further result of an additional quantity of condensate and a consequent dilution of the substance. Such action will also cause a rise of pressure in the condensers which will further increase the heat difi'erence. A decrease of load will have the opposite effect. As

During such times as the load is decreas.

ing, or is below normal, a storage of energy is taking place, first the initial boiler concentrates its solution and as the latter'flows to the first condenser-boiler the temperature in the latter is raised and the solution therein is further concentrated. This effect passes down through all of the condenser-boilers, the system as a whole preparing itself for future draft. 4

In a system of this character it is important, of course, to maintain the proper temperature relation of the various parts. In order to do this I provide an indicator in the form of a thermometer 68 which is located in the pipe leading from the heat exchanger and pump to the condenser-boiler, Fig. 2. Similar devices will be provided for the other units of the system. By observing the indications of the thermometer the station attendants have a guide to direct them in varying the heat supplied to the initial boiler and in varying the surface area of the condensers by manipulating the valves 65.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In a powergenerating system, the combination of an initial boiler. containing a fluid having a higher boiling point than water, a heater therefor, vapor utilizing means, a condenser-boiler which receives exhaust from said means and generates vapor, the condenser portion thereof. containing a .fluid of the same character as that in the initial boiler but having a lower boiling point, and the boiler portion a fluid having a still lower boiling point, the vapor from which is of the same character as that delivered by the initial boiler, and .conduit means supplying vapor from the initial boiler and also the boiler portion of the condenser-boiler to said utilizing means.

2. In a power generating system, the combination of an initial boiler containing a fluid having a' higher boiling point than water, a heater therefor, steam utilizing means, a condenser-holler which receives exhaust from said means and generates vapor, the condenserportion thereof containing, a fluid of the same character as that in the initial boiler but of lower boiling point, and the boiler portion a fluid having a stillilower boiling. point, the vapor-from which is of the same character as that delivered by the initial boiler, conduit 1 means conveying steam fluxes from the initialjb'oilerand also I from said "boiler portion"to thei-utilizing. means where they jointly act, and f a final condenser which ijs in communication" with.

' thefluid utilizing "means and alsofwith the condenser portion of the" condenser boilen 3. In a power generating system, the combination of an initialv boiler containing a solution of caustic potash, a heater therefor,

vapor utilizing means, a condenser-boiler- 4. In a power generating system, the com- I bination of an initial boiler containing a solution of caustic potash, a heater therefor, vapor utilizing means receiving steam from the boiler. a. condenser-boiler, the condenser portion of which receives some of the exhaust from said utilizing means and contains a solution of caustic potash which is weaker than that in the initial boiler, the boiler portion of said condenser-boiler containing Y water from which steam is generated, conduit means conveying the steam from said boiler portion to said utilizing means, and a final condenserwhichreceives the balance of the exhaust steam from the utilizing means. I

5. In a power generating system, the can; bination of an initial boiler' containing a solution of caustic potash, a heater therefor, steam utilizing means receiving steam from the boiler, a condenser-boiler, the condenser portion of which receives some of the exhaust from said means and contains a weaker solution of caustic potash, the boiler portion of said condenser-boilercontaining water from which steam is generated, conduit means conveying the steam from said boiler portion to the utilizing means a final condenser which receives the remainder of the exhaust steam from the utilizing means,

and means for returning condensate from the initial boiler after it has performed useful work and condenses it. the heat given up by the exhaust fluid in the condenser portion being utilized in the boiler portion of the condenser-boiler to gene ate steam from water, a final condenser, a-conduit receiving steam in multiple from the initial boiler and said boiler portion, steam utilizing means receiving steam from the conduit, and a conduit that receives exhaust from the utilizing means and is in communication with said condenser portion and with the final condenser.

7 In a power generating system, the combination of an initialboiler containing a fluid having a higher boiling point than water, a heater therefor, means for utilizing bination of an initial boiler containin afluid having a higher boiling point t an water, a heater therefor, a condenser-boiler,

the condenser portion of which contains a fluid of the same character as that in the initial boiler but of lower. boiling point, the boiler portion of which contains a fluid of lower boiling point than that in the condenser portion, means connected to receive steam in common from the initial and boiler portion of said condenser-boiler, a final con denser, and conduit means for conveying exhaust from said means to both of said condensers in common.

9. In a power generating system, the combination of a boiler containing a substance which, when combined with a solvent, produces a solution which has a higher boiling point than water alone, a heater for the boiler, a turbine that is driven by vapor from the boiler, acondenser-boiler which contains a similar but weaker solution of the same character as that in the boiler and having a lower boiling point and which is heated by the exhaust vapor from the turbine, a conduit supplying vapor from the condenser-boiler to said turbine to assist in driving it, and means for maintaining solutions of predetermined strength in said boiler and condenser-boiler.

-10. In a power generating system, the combination of a boiler that contains a solution having a higher boiling point than water, utilizing means arranged to receive vapor from the boiler and extract energy mama therefrom, a condenser-boiler which contains a solution of the same character as that in the boiler but weaker so as to have a lower boiling point, means for conveying the vapor from the condenser-boiler to said means so that the vapor fluxes act jointly in the utilizing means, means for maintaining a circulation of the solution between the boiler and the condenser-boiler, and means for causing the solution of higher temperature to impart heat to that of lower temperature as it flows between the boiler and condenserboiler.

11. In a power generating system, the combination of an initial boiler containing caustic potash in solution, a source of heat for the boiler, means for converting the vapor received from the boiler into useful work, a condenser-boiler which condenses the exhaust received from said means and vaporizes a fluid contained therein which has a lower boiling point than that in the initial boiler, a conduit conveying vapor from the condenser-boiler to said means in which ,it performs useful work, a final condenser for condensing exhaust received from said means, acooling system for the final condenser, and means for maintaining substantially constant the concentrations of the solution in the initial boiler and in the condenser portion of the condenser-boiler.

12. In a power generating system, the combination of a boiler, a heater therefor, a secondary boiler, said boilers containing fluids which have boiling points greater than that of water, the fluid in the former having a higher boiling point than that in the latter, a prime mover to which both boilers deliver vapor in multiple, condensers arranged in multiple to receive the exhaust I from the prime mover, the heat given up by the vapor in one of the condensers being delivered to the secondary boiler to generate vapor, and a cooling system for one of the condensers.

13 In a power generating system, the combination of an initial boiler and a secondary boiler, both containing fluids which have higher boiling points than water, that in the former being greater than that in the latter, means that receive vapor in multiple from both boilers and utilize the same, condensers also arranged in multiple to receive the exhaust from said consumption means, the heat given up by the vapor in one of the condensers being delivered to the secondary boiler, a cooling system for the other condenser, means for transferring fluid between the main boiler and one of the condensers, and means for conveying condensate from the last named condenser to the secondary boiler. I

14;. In a power generating system, the combination of an initial and a secondary boiler, both containing causic potash in solution but of diflerent concentrations, means for transforming vapor into useful work, said boilers supplying vapor in multiple thereto, a main and a final condenser, the former supplying heat to the secondary boiler to produce vapor, said condensers receiving vapor in multiple from said means, a conduit which continuously conveys a limited amount of fluid of high concentration from the initial boiler to the main condenser, a conduit which continuously conveys fluid of less concentration but in greater amount from the main condenser to the initial boiler, a conduit between the secondary boiler and the final condenser for transferring fluid between them, and a cooling system for the final condenser.

' 15. In a power generating system, the combination of a boiler containing a solution having a higher boiling point than water, a heater therefor, a plurality of condenser-boilers all containing the same kind of fluid but in different concentrations, a final condenser, conduit means connecting all of the boilers in multiple relation, conduit means connecting all of the condensers in multiple relation, a prime mover which receives steam through the conduit means from all of the boilers and discharges its exhaust through the second conduit means to all of the condenser-boilers, and means for preserving the predetermined concentrations of the solutions in the boiler and in the condenser-boilers.

16. In a power generating system, the combination of a boiler containing a caustic potash solution of relatively high concentration, means for heating the boiler, a prime mover driven by steam from the boiler, a condenser containing a similar but weaker solution of caustic potash into which the prime mover discharges, means for transferring a limited amount of the solutions contained in the boiler and condenser from one to the other, a secondary boiler which contains a fluid that is vaporized by the heat imparted to it from the condenser, said boiler being arranged to furnish steam at substantially the same pressure as that from the first named boiler, and a final condenser that receives exhaust vapor from the prime mover in multiple with the first named condenser and inwhich the heat contained in the vapor is rejected.

17. In a power generatingsystem, the combination of an initial boiler containing a fluid having a higher boiling point than water, means for utilizing the vapor generated in the boiler, a condenser for condensin the exhaust from said means, a boiler that receives its heat from the condenser, and a means for maintaining a local circulation of the condensing fluid in the condenser.

'18. In a power generating system, the

combination of an initial boiler containing a fluid having a higher boiling point than water,- means for utilizing the vaporgenerated in the boiler, a condenser for condensing the exhaust from said means, a boiler that receives its heat from the condenser, a heat: exchanger through which hot fluid passes from the initial boiler to the condenser and colder fluid from the condenser uid from the initial boiler, and a pump which receives fluid from the condenser and conveys it to the spray head to increase the circulation of fluid in th. condenser.

20. In a power generating system, the combination of an initial boiler containing a fluid having a higher boiling point than water, means utilizingthe vapor generated in the boiler, a condenser which receives exhaust from said means, a secondary boiler that contains a fluid of lower boiling point than that in the initial boiler and which receives its heat from the condenser, and means for varying the active heating surface of the condenser.

21. In a power generating system, the combination of aninitial boiler containing a fluid having a higher boiling point than water and comprising a base material and a solvent, a heating means therefor, means for utilizing the vapor generated in the boiler, a condenser-boiler which receives exhaust from said means and generates vapor,

the condenser portion thereof containing a fluidof the same character as that in the initial boiler but of lower boiling point, and the boiler portion a fluid having a still lower boiling point, the vapor from which is of the same character as that delivered by the initial boiler, means for conveying fluid between the initial boiler and condenser portion to maintain the fluids therein at the predetermined concentrations, means for varying the effective action of the condenserboiler in the production of steam, a conduit for conveying vapor from said boiler portion to the utilizing means, and a final. condenser in which some of the heat in the exhaust from the utilizing means is rejected.

22. In a power generating system, the combination of a boiler containing a solution of caustic potash, a heater therefor, a plurality of condenser-boilers, the condenser pordenser, conduits connecting the initial boiler and said boiler portions in multiple relation, a steam utilizing means, conduits conveying exhaust. from the utilizing means to said condenser portions and to the final condenser, and pum s for conveying weaker 7 solutions of caustic potashfrom said condenser portions to the boilers to preserve the desired concentration in the latter.

aaeaeaa 23. A thermo-dynamic cycle comprising a it boiler containing a salt of strong heat of solution, condenser boilers, means for translating the vapor of the solution into useful work,. conduits common to the boilers for conveying the vapor at large volume with so loW difl'erence of temperature to said means, and conduits common to and receiving the exhaust from said means and conveying it to the condensers.

In witness whereof, l have hereunto set 25 my hand this tenth day of October 1916.

onannns s. BRADLEY. 

